Heat exchanger



Sept. l, 1970 R. s. WENTWORTHJR 3,526,273

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3,526,273 HEAT EXCHANGER Robert S. Wentworth, Jr., Wilmington, Calif., assignor to Borg-Warner Corporation, Chicago, Ill., a corporation of Delaware Filed July 31, 1968, Ser. No. 749,120 Int. Cl. F28d 1/06 U.S. Cl. 165-74 4 Claims ABSTRACT OF THE DISCLOSURE A heat exchanger having a case with spaced cylindrical concentric walls and an end wall joining said cylindrical walls at the outer end thereof thus forming an annulus, a cover, a blind bore formed by a web across the inner end of the bore of the inner cylinder, fastening means releasably attaching the web, and thus the case, to the cover, and multiple layers of concentric helical coils supported by the cover independently of the case. Each layer of helical coils is separated by a spacer from each other layer, which spacer has an opening at one end through which a portion of the end convolution of the layer extends and is continued back in a reverse axial direction forming the next concentric layer of helical coils. Said coils of all layers are preferably of a single continuous tube with liuid inlet and outlet connections. The cover has uid inlet and outlet ports for admitting and exhausting coolant fluid from said annulus. The helical coils form with the spacer and case, or spacers, a helical ow path for coolant ilow preferably opposite to the direction of ow of uid inthe helical coil.

BACKGROUND OF THE INVENTION This invention has to do with heat exchangers for liquids and the like. More particularly, the present invention relates to heat exchangers of the so-called helical coil type and is for cooling or heating liquids such as water, hydrocarbons and the like carried therethrough in a tube, by thermal transfer to a fluid surrounding the tube and contained in or moved through the heat exchanger. For illustrative purposes, the disclosure herein will be directed to the embodiment of the improvements in a heat exchanger for cooling a liquid, such as an oil used as a lubricant for a mechanical seal, by a coolant, such as water, for which application it has advantages.

In the past, heat exchangers have been subject to objections which have interfered with their use or have made them subject to criticism in one Way or another. One objection has been that, in order to obtain a suliicient degree of eiciency, they have had to be rather bulky which has interfered with their use in limited space. Further, they have been difficult to service, especially after they have been in use for some time and rust or other corrosive action has taken place causing diiculty in disassembly and reassembly.

Previous devices, in order to handle the high pressures present in the system (frequently from 1,000 pounds per square inch to 3,000 p.s.i., or more) have required the provision of an unusually heavy or reinforced case and multiple fastening means attaching the case to the cover at various points around the circumference. Further, the unusually heavy pressures in the helical coils have tended to cause coil distortion and have, in some instances, required the maintenance of corresponding offsetting pressure in the case areas surrounding the coils in order to prevent damage to the coils.

A step toward overcoming some of these objections was taken in United States Letters Patent No. 3,100,523, issued Aug. 13, 1963 to Fernando G. Marrujo. Applicant has,

United States Patent Omce 3,526,273 Patented Sept. 1, 1970 however, overcome all of the above objectionable features in the improvements disclosed in the present invention.

SUMMARY `OF THE INVENTION It is an object of the present invention to provide a rugged heat exchanger for cooling a liquid under relatively high pressure, with the heat exchanger having an unusual compactness with a relatively high capacity and efficiency, and, by reason of its compact construction, presenting limited surface area to internal pressure. The device is suitable for installation in places where space is limited and working room is restricted.

It is a purpose and object to provide an improved case and cover combination wherein the case has an annulus adapted to receive helical coils mounted on or carried by the cover.

Further, it is an object to provide an improved gasket arrangement between the case and the cover which prevents rust or corrosion from interfering with the assembly of the case to the cover, and with the means fastening the case to the cover and which gasket means eiciently seals against leakage between the case and the cover.

It is a further object to provide a simplified means formounting the case to the cover by a single readily operable means, such as a bolt, which is located within a blind bore or recess in the case and thus protects it from inadvertent release or damage.

It is a further object of the invention to disclose an improved arrangement of helical coils. In this connection it is an object to provide a coil comprising a single continuous tube with a layer of convolutions extending axially outwardly and a second layer of convolutions extending axially in the other direction and overlying the rst layer.

It is a particular object of the invention to provide a coil separator or spacer between the layers or coils, and which spacer forms with the coils and the walls of the annulus of said case a multi-direction lluid liiow path for coolant whereby coolant is channeled between each convolution of each coil for the most efficient thermal transfer.

It is an object to provide a modified arrangement disclosing the use of multiple layers of helically Wound coils, each layer separated by a spacer and wherein all of the convolutions of the helical coils are part of the fluid ow path and thus subjected to flow of iiuid used as a coolant.

It is an object of the present invention to provide multiple layers of helical coils supported by the cover and having a spacer between the layers of coils, whereby the case may be readily disassembled and the coils cleaned without disturbing the coils and without the necessity for removing the fluid connections and disassembling the coils, after which cleaning the case may be readily replaced by actuating the single attaching means.

It is another object of the invention to provide drain and vent means for removing the coolant fluid from the case before disassembling, and said vent means being usable for removing any entrapped air when initially illing the case with coolant.

It is an object to disclose a device which may be used in any position or attitude desired, which is relatively inexpensive and easy to manufacture and assemble, is compact, rugged and easily serviced.

Other objects and advantages of the invention will be hereinafter described or will become apparent to those skilled in the art, and the novel features of the invention will be described in the appended claims.

BRIEF DESCRIPTION `OF THE DRAWINGS FIG. 1 is a longitudinal sectional view illustrating a preferred form of the present invention, the mounting bracket being shown in broken lines, and the view being taken on the line 1 1 of FIG. 2, looking in the direction of the arrows;

FI'G. 2 is an end elevational view illustrating the cover,

'or base, of the heat exchanger;

FIG. 3 is a fragmentary sectional view, taken on the line 3 3 of FIG. 2, looking in the direction of the arrows;

FIG. 4 is a fragmentary `sectional view, taken on the line 4 4 of FIG. 2, looking in the direction of the arrows;

FIG. `5 is a cross-sectional view, taken on the line 5 5 of FIG. 1, looking in the direction of the arrows; and

FIG. `6 is a fragmentary -longitudinal sectional View illustrating a modified arrangement of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the structures shown in the various drawings and referring first to FIG. 1, there is here shown a heat exchanger incorproated in a housing 11 having a case 12 and a cover 13.

The case 12 has an annulus 14 formed by the outer cylindrical wall `15 and the inwardly spaced cylindrical wall 16 concentric with the wall 15, with an end wall 17 extending between the outer wall 15 andthe inner wall-16. For purposes of description, the end wall 17 may be described as being on the outer end of said case.

The inner cylindrical wall 16 is joined at its other end, that is, its inner end, with a closure wall or web, herein usually referred to as the web 18, forming with the cylindrical wall 16 a blind bore or recess 19, open at its outer end. The web 18 preferably is drilled or has an opening formed therein as shown at 21 to accommodate a bolt,

-cap screw or the like, 22, or other convenient fastening means. For descriptive purposes the fasetning means will be referred to as the bolt 22, although obviously a cap screw could be used, or other attaching means, but a bolt is believed to be advantageous over other means.

yPreferably a vent hole 23 is formed on the outer end of said case 12 and a vent plug 24 is threaded therein, for purposes which will appear hereinafter.

It is noted in connection with the vent 23 and vent plug 24 that when coolant fluid is iirst pumped into the annulus 14, it is desirable to remove or loosen the vent plug 24 to allow any entrapped air to escape from the annulus 14 land the annulus to fully lill with liquid. Thi-s will prevent undesirable air in the coolant circuit, which ymight inten -fere with the system or detract from the cooling effect.

O-ring grooves 25 and 26 are provided at the inner end of the outer cylindrical wall 15 and the inner end of the inner cylindrical wall 16, respectively, said grooves 25 and 26 being circumferential, one on each side of the annulus 14 and each groove being provided with an O-ring for sealing against uid leakage from the annulus 14. The O-ring for each groove seats against what may be described as the inner face of the cover 13 when the case 12 is assembled to the cover 13. Obviously, other gasket means can be used to prevent leakage of fluid from the annulus r14 at the inner face of the cover 13, but O-rings are effective, inexpensive and easily installed.

As shown in FIG. 1, the cover 13 has an opening 27 therethrough to accommodate the attaching means, namely, the bolt 22; and the bolt 22 may be provided with a washer 28 and nut 29. Such bolt arrangement has advantages over a cap screw in that the bolt 22 may be released by a socket wrench or the like extending into the blind bore 19 from the outer end thereof or the nut 9 may be removed from the other end should there be more room for a tool for this purpose. Obviously, the o-pneing 27 could be threaded to receive a cap screw, although it is not believed necessary to illustrate such alternate arrangement.

The cover 13 also has a hole 31 and a second hole 32, as shown in the illustration of FIG. 1, through which, as will hereinafter be described, extends tube `means carrying liquid to be cooled.

It will be noted that, as shown in broken lines in FIG.

4 1, the cover 13 has a mounting bracket 33 whereby the cover and case assembly may be mounted at any convenient location and at any selected angle.

The hol-es 3l and 32 are preferably tapped to receive fittings 34 and 35, respectively, containing split bushings 36 and 37, respectively, for the reception and retention of the tube extending through each hole and the hex nut 38 for the fitting 34 and hex nut 39 for the fitting y35 for retention of said tube and sealing of said opening against leakage.

Referring next to FIG. 4, there is here indicated the cover 13 with a fragmentary view of the case 12, but illustrating the inlet port 41 and the outlet port 42 which extend through the cover 13. The inlet port 41 is tapped to receive a connection for a conduit (not shown) for coolant liquid, such as water, for input into the annulus 14; and the outlet port 42 is tapped to receive a connection for a conduit (not shown) to carry off the coolant fluid.

As referred to in FIG. 3, the cover 13 has a drain hole 43, hereinafter referred to as a drain 43, with a drain plug 44 threaded therein.

Referring again to FIG. 1, it is noted that there is provided a layer of helically wound coils, in the example shown being coils 45, which, in actual practice, are usually wound on a mandrel during manufacture and which extend axially from the inner end to the outer end of said assembly and a second layer of helically wound coils, in the example shown being coils 46, which are integral with, but -wound axially from, the outer end to the inner end of said assembly. The coils 45 and 46 are formed of one continuous tubing and preferably do not have any joints. In other words, the tube is a continuous integral, one-piece tube with no welded, brazed or soldered joints, and, in actual practice, is usually either copper or stainless steel, thus eliminating any likelihood of leaks developing therein due to galvanic action or the stress of heavy pressures destroying the joint. The outer layer of coils, that is, the layer comprising the coils 46, has its end extended through the hole 31 and is mounted therein by the fitting 34, split bushing 36 and associated parts so that it is securely held in position with no leakage therearound. The other end of said coils, that is, the inner end of the inner coils comprised of the coils 45, extends through the hole 32 and is similarly held in place by the fitting 35 and associated parts. Thus, the two layers are xedly attached to the cover 13, and the cover 13 serves to support or carry the coil assembly independently of the case 12.

It will be noted that the coils are separated by a spacer or sleeve 47, which spacer is preferably made of sheet metal or other material compatible with the metals of the coils and the case, thereby reducing any gal-vanic action, tending to corrode the coils, the spacer and the case, to a minimum. The spacer 47 has a portion of its outer end eliminated or cut away, as indicated, to form an opening 48 for a transition turn of the tube carrying it from the inner layer to the outer layer. In other words, usually 1/3 to 1/2 of the end of the spacer sheet is cut away axially toward the inner end of the assembly whereby the end of the coil layer 45 is extended over the spacer sheet and is wound axially in the other direction to become the layer 46. In practice, as mentioned before, the tube forming the coils is usually placed on a mandrel and the coils are wound axially to form the inner layer of coils 45 and, when the end of that layer is reached, the spacer 47 is placed on top of the layer and the winding continues, but in the opposite axial direction. In this way the outer layer is superimposed on the inner layer with a spacer therebetween, there being an opening or cut away portion of the spacer for the transition segment of the tube between the two layers and also to provide, as will be described hereinafter, a gap or opening for the iiow of liuid. Preferably, at least in the form shown in FIG. 1, the spacer sheet between the two coils extends axially from a position abutting the face of the cover 13 to a position abutting the end wall 17, except for the cut-away portion 48, which has its outer end spaced from the wall 17.

With the above arrangement, coolant enters the annulus 14 through the inlet port 41 in reasonably close proximity to the hole 32 from which the coil 45 discharges, is carried in a helical path between the spacer 47 and the inner wall 16 of the case, past each of the convolutions of the layer of the inner coils, that is, the coils numbered 45 in the drawing, to the outer end of the annulus adjacent the end wall 17, at which time it flows through the opening or cut-away portion 48 of the spacer and between the spacer 47 and end wall 17, and continues in a reverse direction to flow helically between each of the convolutions of the outer layer of coils, namely, the convolutions 46, and is discharged from the annulus 14 through the outlet port 42. It is thus seen that the coolant uid enters the annulus 14 in a position to exert the most cooling action, due to the fact the coolant has not been subjected to thermal -transfer of heat, on the fluid to be cooled which is flowing through the tube from the coils, at the outlet end of that tube, but continues to thermally displace heat from the various convolutions in the entire flow path through the heat exchanger. The coolant fluid may thus be described as having a flow path opposite that of the liquid to be cooled, and which is both helical and two-directional axially to obtain the maximum eiciency in heat transfer.

It is noted that FIG. 2, which is an elevation of the cover 13, indicates the positioning of the inlets and outlets for the coils carrying the fluid to be cooled and for the flow path of the coolant uid.

In actual practice, in order to reduce or eliminate galvanic action, the case 12 and the face of the cover 13 are preferably covered with a layer of porcelain. This has not been illustrated herein.

It is noted that the heat exchanger of the present type may be used with relatively high pressures in the tube carrying the liquid to be cooled, frequently as high as 1,000 to over 3,000 pounds per square inch. In such arrangement the case 12, and the spacer 47, both exert a limiting effect on the expansion and distortions of the layers of coils, thus eliminating or reducing the need for any excessive counter pressure in the coolant. The case, the construction of which was described above, may be said to be composed of inner and outer spaced concentric cylinders 15 and 16 connected at their outer ends to form a closure wall 17 and with the inner circumference of the inner cylinder 16 closed by a web or an end wall 18. Such arrangement has an unusual strength for weight ratio, presenting reduced surface area subject to internal pressures, not requiring extra ribbing, gussets, or other reinforcement, and is able to withstand relatively high internal pressures. The web, which may be solid except for the attaching opening 21, or may be merely an integral diametric or chord-like strap, being located at the inner end of the bore forms an attaching element so that there is no need for special alignment and centering during assembly or reassembly after cleaning, as would be required if circumferential bolts or other attaching means were used. Further, there is little or no area for corrosive or foreign material to interfere with the seals and close iit at the inner end of the case. Thus, the single very effective bolt forms a readily releasable attaching means.

It is frequently necessary to clean such an arrangement internally, and this is usually done by draining the annulus through the drain plug 44, preferably opening the vent 23 to expedite such drainage. This removes the pressure of the coolant liquid and most of the coolant, without disconnecting the coolant iittings or connections. The bolt 22 is then released and the case may be moved axially oi of the coils, thus freeing them from the annulus without the necessity of disassembling them from the cover or of releasing the fittings or otherwise interfering with the uid connections to the tube forming the coils. The user may then clean the coils mechanically, such as with a brush or other means, clean the case, and replace it so that the coils are reinserted into the annulus and the bolt 22 extends through the base plate. Tightening of the bolt 22 or its nut then reassembles the unit.

Referring next to FIG. 6, this is a modified arrangement illustrating the use of numerous layers 145, 146, 149, 151 of coils. Any number, which is usually a multiple of two, may be used, depending only on the desires of the manufacturer and the available space in the annulus.

As shown in FIG. 6, the case 112 corresponds in principal and construction to the case 12 of FIG. 1, and the annulus 114 corresponds to the annulus 14 of FIG. 1. The bolt 122, blind bore 119, vent hole 123 and plug 124, bolt openings 121 and 127, O-ring grooves 125 and 126 containing O-ring seals, web 118, and other essential parts of the case are the same as those of the case and cover of FIG. 1. However, the layers of coils have been increased to four ,-(any suitable number, usually a multiple of two may be used). Here the coils form the inner layer, coils 146 form the second layers, coils 149y form the third layer and coils 151 form the fourth layers. Preferably, the tube of which the coils are formed is an integral one-piece tube, and the convolutions are wound helically axially outward for the first layers 145, axially inward for the second layers 146, axially outward for the third layers 149, and axially inward for the fourth layer 151. The spacers 147, 152, 153, one of which is between each pair of layers 145, 146, 149, 151, are open alternately at opposite ends 148, 154, 155, and, as here shown, are indicated as spacers 147, 152 and 153. In this arrangement the fluid ilow path of the coolant iiuid would (although the entrance is not shown in this ligure) enter adjacent to the inner end of the inner coil 145, flow around the inner coil 145 and between the inner wall 116 of the annulus and the spacer 147, to the outer end 117 of the annulus 114 whereupon it would reverse and ow through the layer of coils indicated as 146- between the spacers 147 and 152 to the inner end of the layer, would ow through the opening 154 at the inner end of spacer 152 into the third layer of coils, here indicated as 149, and between the spacers 152 and 153 to the outer end 117 of the annulus 114, out the opening 155 at the end of the spacer 153 and axially to the exit at the inner end of the cover 113 between the spacer 153 and the outer cylindrical wall 115 which forms the outer wall of the annulus 114. Thus, the iiuid iiow direction would reverse itself axially for each layer 145, 146, 149, 151 of coils. Should the static pressure required to cause the coolant to flow become excessive, the spacers 147, 152, 153 or some of them could have the size of the opening 148, 154, 155 caused by the cut-away thereof increased to permit a wider area for the fluid path. This might be either a lengthwise increase in the opening 148, 154, 155 or a circumferential increase in the opening. More coils, of course, tend to reduce the amount of liquid that can flow through the tubing, for any given diameter of tubing, and thus the heat exchanger can be used to regulate to some extent ow from a pressure vessel to the tubing-that is, ow of uid to be cooled.

It is understood that this arrangement lends itself to other uses, such as heating the iluid surrounding the coils, in which event it might be desired to have Steam, hot water or other hot material flowing through the coils, or the arrangement could be reversed and a hot liquid could be channeled through the helical ow paths of either thedevice of FIG. l or the device of FIG. 6', or any modification for the purpose of heating the iiuid in the coils. Obviously, this is an equivalent use, as a generality. The device herein described, as shown in FIG. 1, has been adapted to the cooling of a lubricant, such as water, oil or the like, used in lubricating mechanical seals, and for that purpose is exceptionally valuable.

While the specific details of the invention have been herein shown and described, changes and alterations may be resorted to Without departing from the spirit of the invention.

I claim:

1. In a heat exchanger or lthe like having in combination a case, cover means, means attaching said case to said cover means, a helical tubular coil in said case and having uid inlet and outlet connections, those improvements wherein:

(a) said case has spaced concentric inner and outer walls joined at one end by an end wall, thus forming an annulus open at the other end;

(b) the outer surface of said inner wall having a web across the end remote from the closed end of said annulus, thus forming a blind bore;

(c) said helical tubular coil mounted on said cover means and extending into said annulus, and said helical tubular coil comprising a continuous tube in at least two layers having its ends extending through said cover means;

(d) sleeve means concentric with said inner wall extending substantially the length thereof and separating said coils so as to provide a helical flow path in said annulus for coolant fluid flow;

(e) uid inlet and outlet ports through said cover means for the passage therethrough of coolant fluid into and out of said annulus;

(f) said means attaching said case to said cover means consisting of means releasably attaching said web to said cover means; and

(g) whereby upon release of said means releasably attaching said web to said cover means, said case may be removed from said cover means and said helical tubular coil for cleaning and service without disturbing said helical tubular coil.

2. A heat exchanger or the like as set forth in claim 1 wherein said means releasably attaching said web to said cover means comprises single bolt means extending through said web and said cover means.

3. A heat exchanger or the like as set forth in claim 1 wherein gasket means such as O-ring seals are provided between said case and said cover means and surrounding the open end of said annulus.

4. A heat exchanger or the like as set forth in claim 1 wherein drain and vent means are provided for said annulus.

References Cited UNITED STATES PATENTS 2,127,732 8/1938 Heitrnan 165-160 2,160,898 6/1939 Pei 165--160 X 3,100,523 8/1963 Marruvo 165*160 ROBERT A. OLEARY, Primary Examiner T. W. STREULE, Assistant Examiner U.S. Cl. XR. 

